Multiplex signaling system



May m, 1925.

M. B. LONG MULTIPLEX SIGNALNG SYSTEM may 19, 1925;

M. B. LNG

MULTLPLEX SIGNALING SYSTEM lll innemen s. oorernnr,

' rennes nesten LONG, OF GLEN RIDGE, NEW JERSEY, SSIGNOR T0 WESTERN ELECTRIC 'ENCQB-ORATED, OF NEV YORK, N. Y., A. CORPORATION 01' NEW YGB-K.

Monrizrnnx srenentno srsrnnr.

Application filed February 20, i924. Serial No. 693,998.

To 0U iff/0m may concern:

llc it known that l, Mnniucn B. Lone, a citizen of the United States of America, residing at. tillen Ridge, in the county ore Essex and State of New Jersey, have invented certain new and useful improve ments in E'ultiplex Signaling Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to multiplex sig-- -naling systems employing a plurality ot currents or Waves oi dinerent frequencies for the transmission or" signals or for similar purposes.

A general object oit the invention is to provide a system in which a high degree oi" selectivity is obtained between the Various message waves. with an accompanying economy in the frequency range, and in which :i more economical as Weil as a more cllicient construction and arrangement ot the various selective elements of the system is realized.

t related object othe invention is reduee the number of different types filters employed in such a system.

Another object of invention is simplify the design and construction fi lers employed in suclrsysterns.

'ln multiplex signi-lling systems in' which transmitted energy is 'in the form of Waves or oscillations` nu'idulated with the signals to he transmitted, 'a plurality of such waves, each of a distinctive to of to of fremiency, are transmitted over the saine line. ln such systems, wave filters and' in some ceses tuned circuits are used to' separate the various distinctive frequencies one 'from another. I

lt has heen demonstrated that the transmission of several kinds of signals may oe carried on at the same time :in looth directions through the system, the different kinds oi' signais and the diiilerent directions being distinguished by the different frequencies' employed. Such a system is, disclosed in :in applicationpt J. lil. Horton, Serial No. 488,297, tiled .luly 29, 192i. ln that system, the transmissions ot en ordinary telephone line, Morse. telegraph and other signaling' currents Within or heloiv the ordinary tele# phone range are separated from the carrier transmissions by the use of bread bend filters, or high frequency composite ilters, The carrier. transmissions comprising tein accordance circuits that operate to ampliy Waves inv that direction. l

lt has been-suggested that economy in the construction of filters can he obtained by building each filter up fromv elements that are sufficient 'for the particular load requilements, such as the frequency, current strength and attenuation. rlhis was pan tieularly true of the older types of filters which required a largo number of elements. Filters more recently developed employ a lesser number of elements but the saving y in filter material is offset to a considerable extent by' the greater' cost of engineering such a system involving designing each filter from its individual requirements. According to the invention, it is found possible to retain the economy resulting from the individual design ot the filters and at the same time very materially reduce the manufacturing and engineering costs of the system, thus securing material economy in construction Withoutsacricing efficiency or any of the advantages of former systems.

' In a multiplex system to which the invention is particularly applicable, the repeuter lilters consist of a pluralityof sections divided into two `groups by means of an amplifier, thus connecting` the repeater element to botlrends of the line through sections of the selective lilters. In such a system, the sections ot one ilter group have a higher transmission eiciency than those of the other group 'for the same load for the purpose ot eliminating harmonics and interniodulation currents. The input and output repeater filters must be designed to transmit frequencies within aV givenrange anal to effectively suppress all frequencies outside or this range, and atthe same time must have suoli an attenuation that the combined effect ofthe tilters will prevent. singingat thewrepeateif'fior the desired range inici-line repeater station; and Fie.

v necessitated the eonstuotion of e.

ancldistinct filter feti' eeuli filter position in the system.

ln aocorfience wi'li e. feature of the inventiomtbe nuinbei oi"- different types oli filters in o, multiples signaling system of 'lle above type is mstelfiuily reduced by ciesigning the filters Ain accordance With the filter requirements et uitlenen?, points in the system.

Since tile inflivitluul filters are located et diferent points in 'the system to accomplish di'erent puposes, they eocoi'niingly .beve different xequireinents, either individually i1 in groups, enel in ueoord'ance with the invent-ion one filter of u group made iden tical with e single litter ut another position and allot-lier filter ot the group so designed that when Combined with the other tiltei oi" 'the group the combination will moet the `group requirements More specifically, the lter o the signaling system is liest, flesignefi to lneetmertuin givenI iequii'en'zents and. un identioel filter is used us tbe input filter of the repeateiiioi vtbe saine gioup of frequencies. The output, repeater filter is then so designed that the Combined efreceivingl grouping -iyfeet. of tbe input and outputV repeater tilt-eins Will prevent enigme; at the i'epeutei'.

The output repegxte lter is also designed to have u predetermined impedfinoe require-4 ment so that un identical'iltei can be usecl :1s the sending grouping filter.

Other feature* und' advantages of the invention will appeur from the consideration of the following fleseriptiou teken in connee-tion with the :ueompunymg drawings, in which,

Figs. l. 2 and lIl, when plueecl end to encl in the order named, with et the left2 illustrate fliegrunuuutieelly oneoembodunent 'ei the invention. Fig'. l shows the Currier telegraph und Currier telephone apparatus ut one terminal station; Fig. il the eppeutus und `seleotiw oil-cuits et e f, the cum'ier telephone ami ce1-rie? telegraph teu minul apparatus ai; the other terminal stotion.

into the common line ML.

The West terminal station is connected-to vJanuuiy, 19223.

the common ti'uusmissiou line; Mill by means specifically mentioned, muy be of ihe' typedisclosed iu. li'itish .Patent 18,l98 muy be eonstiiuffted es composite wave lters as disclosed in Part 3 of en etiele on the Theory and design ot unieifm and coinposite :electric wuve-ilteis'. by @tto al. Zobel,

the Bell System Technical .lounsh oil' These consist, in gen eral ot e plurality of sections having series :mtl shunt ieiotzinces. flesigne, ecofling 'to Weil known laws, loi tbe range o" frequencies oil 'che eu'ents which the illers ure to transmit. Filters of this type are known :is Iuppiession filters und zure particularly advantageous Whose u sharp eut-oli between frequencies in the tz'ensmittecl and suppressed ranges 'is desired. Filter' l0 is adapted to pass with substantially negligible attenuation. all. currents having frequencies ot 3330 cycles and ubove7 unil to greatly attenuate Currents having frequeng oies less thun 3330 cycles, while iiltei' il is :ulupteal to pass with substantially negligible uttenuetiou, ell currents having he quencies oit 2800 Cycles or less und to highly utteuuute ull eui'ieuts having frequencies above F2000 cycles. @Suele en um'angement of iltoi's is'shoun in Fig. l5 of e. pepe? entitled lni'iiei current telephony und teleg- 'uphv"" hv li). H. Colpitis und t). Bladi! well; published in the Transactions of the .fime'iceu Institute of Electrical Engineei's, Volume 40. llQl. These lilters serve to seperate the noimu'l transmission of an ordinary telegraph und telephone line L2 'from the Currier transmissions ofthe Currier eir- Cuit CU2.

ln ouder to separate the Currie? telegraph transmissions from tbe eeiiiez' telephone transl'x'iissions, tilteys l2 un l proviciefl; Filter l2- is e low pass liltexf adapted to pass with substantially negligible attenuation7 frequencies of 0000 cycles und under, und to l'iighly attenuate ull frequencies above that velue. Filter 13 is a high iltei' adapted to pass with suiistuutially 'negligible attenuation 'frequencies o; 10,000 v cycles und above, @nel to highly attenuate 'all frequencies below that value. These liltei's will herein-after be celled Carrier grouping filters.

Foi' the oai'rier telegraph. transmission, filters lli and 'l5 are provided to separate the li'equeiuzies used ii'or transmission from the stutiou from those used for leception theifeut. Filter M; is a low pass filter adapted to pass with substantially negligible attenuation,*frequencies of 5500 cycles and under, enti 'to highly attenuate all frequen. cies above 5500 cycles. Filter l is s high iso git)

if' ,ceases IS590 cycles and all frequencies above that value and to highly attenuate all 'frequencies below v6500 cycles. These filters will hereinafter be called carrier telegraph menging filters. Filters corresponding to nlters l@ ancl l5, and the associated transniit'ingr and receiving apparatus, are also provided at the West station for the ca telephone transmissions.

Timed selec-rive circuits S1, Sg, etc., are providel to separate the frequencies sell ca? ier telegr 'ph transmitting at the West station. lt desired, wave filters may he useci for this purpose instead of tuned circuits.

R1, R2, etc., are also e1nselective telegraph transmit:-

ass filter Il by means ci.' transformer lect-ive receiving circuits are high pass filter, l5 ley means ansrorrner .L n v anni the I3 VIVhe carrier telegraph terminal aglparatns shown in Fi". l `s similar to the terminal apparatus sho in Fig. 55 ci the Colpitts (i qlsclr'-.vell paper, supra. The sending cuits each comprise an oscillator and arnl and a sending relay lt) connected ecsive selective sending circuits j etc., The receiving circuits each cornan amplifier and rletector 2Q and a receiving ay 2l connected to the respeci ,electric receiving circuits R1, R2, etc. he relay i9 and the receiving re- 21 are each associated With ordinary horse telegraph apparatus in the manner Well understood in the the carrier repeater station, sli Wn in 2, the low `frequency telegraph and telephone line La and the common carrier circuit CCB. are connected to the common line means of a high frequency comt conn rising the low pass tilter high pass'lter 24. Filters 23 and nlar respectively to iilters l1 and `ier grouping' filters are also prointi comprise a low pass filter 25 and pass filter 25. vFilters 25 and 26 are .similar respecti vvely to filtersl and 'i3 on l For repeating carrier telegraph signxls east and west repeater elements TRE ano; Till?, respectively, are provided. e'oeatin 'f elements suitable for this purpose are described in connection with Figs. 2l and 22 oli` the Colpit'ts and Blackwell paper, supra. Carrier telegraph transmissions east are separated trom transnlissions West by low pass filters 27 and 28 and high pass filters 29 and 30, respectivelr. F'tcrs 27 and 28 are adapted to pass the saine range of frequencies as filter lll of Fig. l, 'and filters 29 and 30 are adapted te pass the saine range oi frequencies as-'ilter l Y'33 and lon n ss i tively to high pass litter l0 and lowl of@ i Fig. l. he arrangement et the repeater to selectively transmit currents of the clef' sirecl range of A)frequencies to the exclusion ot currents of other frequencies.

Carrier grouping filters' 3l and 32 separate the carrier telegraph transmissions from the carrier telephone transmissions at the cast end ol the repeater. -`Filters 31 and S2 are-similar to and are adapted to pass the saine range of 'frequencies as filters l2 anfl 13, respectively, of Fig. l. A high frequency coin'posite set comprising high pass ,filter 3S and low pass Y.filter 54 is provided to connect the connnon carrier circuit @C4 and the ordinary t .lf to the common line "i3/""1, ll'igli pass filter plter similar respecfilter ll ci Fig'. it. At the repeater station are also prorideil carrier telephone repeater elements corresponding to the carrier telegraph repeating elements described alcove.

The east station is similar in arrange- .inent to the West. station, A high :frequency composite set comprising; the high pass filter and the low pass iltert connects the connnon carrier circuit @C5 and the ordinar)v telegraph and telephone line L to the common line ML. Filters 35 and 3G correspond respectively to lilters l0 and ll of Fig. l. Low pass filter 37 and high pass filter 3S are the carrier grouping filters at the east station and cor to filters l2 and 13 ot' the west. station. Low

pass filter 39 and high pass filter 40 are thel qnencies of 550() cycles and below, and to v greatly attenuate currents having'frequencies above 5500 cycles, Wlnle filter l() is adapt` ed to pass with substantially1 negligible ettennation all cnr-rents having' frequencies oit 650i) cycles ancl alcove and to greatly attenuate currents having frequencies less than (2500 cycles. Selective transn'iitting;a circuits RSS. liti?, etc., are coupled to the high pass filter l0 by means ot transformer lll, and

correspontl to the transmitting select-ive ein.

cuits S1, ctc., ol the West station and cooperate with the receiving selective circuits llh l2, etc., of that station. The rcceivingseiecire circuits Elli, lli?? etc., oi

he east station are coupled to the lon7 pass tt r 39 hy means ot transformer i spend. to the roccia A- che., of lic fa ,e 'with the transnn aiegrapli and telephone line respond respectively :respective brunch.

S1, S2, etc., of that-station. The carrier telegraph terminal zipinrrutus :it the cust station is similar to that en'iployetl ut the West station, euch ofthe sending circuits iucliuling un oscillator and amplifier #t3 and a sending relay lill, und each of the receiving circuits including e receiving reilly 4-5 und un amplifier und detector 4G connectetl teA the respective tuned circuits. `Filters ecrresponding; to filters 3S) and lill, and the essoelated receivingl und transmitting apparutus are also provider?. et the enst station for the carrier telephone 'transmissions ln accorineelwith the liailiourn patent, supra, the amplifiers Till@ mul Tlillr at the repeater station ot Fig. 2 :ire interposed het-Ween the input und output repeater filters 27, 28 und 3G ,inespertiVeliny so that part oi the filter sections connecteflto-the input circuit et the ,amplifier undv the ref vi'nuincler ot' the sections ere connccteil to 'its outputcircuit. By means of this errungenient beth units und 28 and units 2) and 30 serve to prevent transmission of currents ofthe frequencies assigned to the other brunch, anti in eelclitioii units'QS unil 29 serve to suppress harmonics cnil interino( ulution currents proiluccil by the repeater elements Tllll uml Till?, respectirelyv` which nre et' frequencies outside the normal range of its it has heretofore been the practice to construct each ot the trans'- mittine filters ist und fill and the receiving grouping' ilters :intl 39 es Well as the rcpeuter filters 2, 2S, 2?; und BG with respect to their own particular Vfunctions without regard to their conil'iinecl relation in the tem. As a result ot' this practice, e greet runny ilitlerent types et filters have yheen necessarily employed. in accordance with a feature of the invention,v the receivii'igg and sending,vv group-ing filters und the input and outpfut repeater filters r the suine group o frequency src euch designed with reerence to the requirements of the others. The receiving grouping'` filter of euch crunch or channel has both an impedance und un uttenuation requirement and' is teken u basis of design 'l'or all of the other iilters. The inputuinl outputlilters :it the repeater must meet certain combined requirements,

and therefore, the input filter is nnule i len tical to the receivinggrouping filter und the' output filter is so designed us to ineke the combination rnc'et the combined repeater rcquiremcnts. The transmitting grouping lilterlms mainly :in impedance requirement and the output repeater Filter is given this impedance requirement and cnn therefore be used as the transmitting greui'iing filter. B v this arrangement two types of iilters only are required for tour filter positions in the system.

In the system herein shown and described, the receiving grouping filter 39 is consiructed in accordance with the iinperlanee enel attenuation requirements this position. This filter may be of theeoini'aosit-e were lilter type described in the ,ohel erticle, supra, anni consists oie plurality of sections having series und shunt n.ictsnces clesigneol to gil'eutlie `lilter thel required inipetlence and attenuation churecteristics. The velues the various eleniei'its of the fiilter 39 for ,the given range et requeucies is shown hy Willy oi' illustrer-t on in the draw ing, This liiter is taken is e of design fer the filters lll, 27 and 28. The input filter 27 und the output ,filter at the repeater station must. meet certain conihinecl requirements. To meet these requireioents the input filter 2"? `is matie identical te the receiving' groupinw filter 39, es indicatecl in the drawings, incl the eutpueilter 28 is then designed tu have such en attenuation tliut the corrhinecl effect et the filters sull 28 'vent singing et the repeater for ed range et trensinission. The gretig-fing; 'tilt-er le.' has mainly en impedance requirement enti the' out-put re-` peater iilterl is given. this iiripeilance requirement, and therefore .the sending group ingr tilter may he identical to the output repeater filter 1 rllhe high pass grcupinggj A,liters and e0 :nul repeater filters 29 end 30 ure construct- 'erl in the seine manner es 'the grouping filters cuter filters 217 end 28.

ist anti 39 unil 'the rep The receiving greupin lter l5 is .first constructed in accordance- Witli its impedance und attenuation requirement and is taken as :i liusis ot design for the filter 29, 30 und 40, The input repeater filter 30 is made identical te the receiving grouping lilter l5 and the output repeater lilter is so designed :is to multe the conihinecl eft'ect of the filters 29 and 3l) meet the repeater requirements, takino` 'into consideration the impedance rcuuircincnt Jfor the filter-40. The filter 4l() is then meile identical to the output repeater filter 29. ,ily ineens of this arrangement, only tivo types ci tilters ere required for the four lilter positions lf3, 29, Il() und 4t), as well :is two mlilitionul types olil filters -for the four liltcr positions lll. Q7, 28 und 39.

The invention has heen illustrated in con-- nef-tion with the carrier telegraph circuits oi the multiplexv signaling s'vstcnn hut it is to he unilerstood that it is equally applicalilc to, :intl in taetluis been succcssfull).Y usedin, the carrier telephone circuits, only so much ol' the currier telephone circuits heine shown :is is thought necessary to u 'complete uiulerstunding oll the invention. The transmitting :intl receiving groupiificr filters ol the carrier telephone system corrcsponding` to the transmitting' and receiving carrier telegraph grouping filters 14, 40, 15 emi 39, respectively, are not shown in the drawing, but muy hey so constructed' with relation to mtl RSU

rasante the input and output lters at the carrier telephone repeater, in accordance with the 1nvention, that the number of types of filters required in the system is materially reduced.

The circuits and systems that have been illustrated and described in detail should be considered as merely typi'fying' one form of the invention but are not to be construed as limiting the invention, the scope of which is defined hy theI appended claims.

l/Vhat is claimed is:

1. In a multiplex signaling system, e. transmission line, stations thereon, a grouping filter at one station, a grouping filter at another station, and a repeater connected in said line and comprising an input filter identical to one of said grouping filters and an output filter identical to the-other of said grouping filters, said output filter having a different transmission efficiency for large currents than said input filter.

2. In a multiplex signaling system, al

transmission line, stations thereon, a transmitting grouping filter at one station, -a receiving grouping filter at another station. and a repeater connected in said line and comprising an input filter identical to said receiviuf. r groupingfilter and an output filter identical to said transmitting grouping filter, said output filter having la higher transmisson efficiency for large currents than said input Hlter.

3. Ina multiplex signaling system, a transmission line, a grouping filter at one end of said line, a grouping lter at the other end of said line, and a repeater connected in said line and comprising a plurality of scclious and an amplifier dividing said sectiwns into two groups, the sections of one grnup being identical to one of said grouping filters and the sections of the other group being identical. to the other grouping filter. the sections of the second group having a, different transmission efficiency for amplified l' currents than the sections of the first group for the same load.

Il. In a multiplex signaling system. a transmission line, a transmittingr grouping filter at one end of said line. a receiving grouping filter at the other end of said line, and a repeater connected in said line and comprising a plurality of sections and an amplifier dividing said sections into two groups, the sections of one group being identical. to said receiving grouping filter and the sections of the other group being identical to the transmitting grouping filter, the sections of the second group having a higher transmission efficiency for amplified currents than the sections of the first group for the same load.

5. In a multiplex signaling system, a transmission line, a grouping filter at one end of said line, a plurality of transmitting channels' connected to said lter, a second grouping filter, at'the other end of said line, a plurality of receiving channels connected to said second filter, and a repeater comprising input and output filters having different transmission efliciencies connected to said line, said input filter being identical to one of said. grouping filters and said outputl filter bein identical to the other of said grouping lters.

6. In a multiplex signaling system, a transmission line, a transmitting grouping filter at one end of said line, a plurality of transmitting channels connected to said filter, a receiving grouping filter at the other end of said line, a plurality of receiving channels connected to said receiving filter, and a. repeater comprising input and output filters Ahaving different transmission elhciencies connected to said line, said input filter being identical to said receiving grouping filter and said output filter being identical to said transmitting grouping filter.

7. In a multiplex signaling system, a transmission line, a transmitting grouping filter `at one end of said line, a'plurality of transmitting channels connected to said filter to transmit currents of different frequencies through it, a receiving grouping filter at the other end of said line. a plurality of receiving channels connected to said receiving filter to receive currents of different, frequencies transmitted through it, and a repeater comprising input and output filters having different transmission efficiencies connected to said line,` said input filter being` identical to said receiving grouping filter and said output filter being identical to said transmitting grouping filter.

8. In a multiplex signaling system, a transmission line, a transmitting 'grouping filter at one end of said line, a plurality of transmitting channels connected to said filter to transmit currents of different frequencies through it, a receiving grouping filter at the other end of said line, a plurality of receiving channels vconnected to said receiving filter to receive currents of different frequencies transmitted Athrough it, and a repeater connected in said line comprising a, plurality of sections and an amplifier dividing said sectionsinto two groups, the sections of one group being identical-to said receiving grouping filter anda the sections of the other group being identical to said trans-- mitting grouping filter, the sections of the second group having a higher transmission efficiency for amplified currents than the sections of the first group.

In AWitness whereof, I hereunto subscribe my name this 19th day of February A. D.,

1924i. y MAJRICEv B. LONG. 

